Using procedures that we have already established, we will isolate several variant subpopulations of tumor cells from a common parent tumor. Each of the variant subpopulations will be characterized with regard to several in vitro properties including: 1) growth rate, saturation density and anchorage dependence; 2) migratory activity; 3) adhesiveness; 4) content and release of hydrolytic enzymes; 5) surface structure and 6) invasiveness. The variant subpopulations will then be compared for ability to produce tumors in syngeneic mice and for ability to metastasize in these animals.